This invention relates generally to clip-type electrical terminals, and more particularly to an insulation displacement terminal of this type.
Generally speaking, insulation displacement clip-type terminals are devices for engaging a solid conductor insulated wire to make electrical contact therewith. These clip-type terminals are generally relatively flat pieces of metal having two integrally formed resilient arms which provide a conductor receiving slot therebetween. The insulated wire is forced into the slot, which is of a width considerably less than the diameter of the conductor. The process of inserting the conductor into the slot results in a penetration of the insulation so that electrical contact is obtained between the slot edges and the conductor. Wires may be quickly terminated by this sort of clip terminal because the need for prior stripping of the insulation is eliminated.
Clip-type terminals of this type are most frequently utilized in telecommunications applications wherein large numbers of conductors are to be terminated as expeditiously as possible. In typical installations, many hundred such terminals may be provided, mounted in suitable terminal blocks or the like, for receiving large numbers of telephone conductors for cross-connect and termination purposes.
In many terminals of this type, the penetration of the insulation is achieved by a crushing of the insulation which may be combined with a certain degree of abrasion or tearing of the insulation resulting from the relative movement of the conductor with respect to the edges of the slot formed in the terminal. In many of these prior art devices the entry to the slot is a relatively smooth V-shaped opening such that the insulated wire exerts a camming action which forces the resilient arms apart. However, in such devices, all of the insulation is not necessarily removed around any given portion of the solid conductor. In some instances, and particularly with relatively small diameter wires, there may be some insulation remaining between the conductor surface and the slot edge, either in the form of discrete particles or in the form of a thin film, either of which may unacceptably increase the resistance of the connection.
In other terminals of this type, the insulation is cut by cutting edges which extend generally perpendicular to the axis of the conductor; however, cutting edges so placed usually also cut into the conductor core somewhat. This can lead to unacceptable conductor breakage or an unacceptably low pullout force of the conductor or both.
In the majority of communication-type uses as described above, it is desirable to provide for frequent insertion, removal and reinsertion of different conductors with respect to each such terminal. Thus, it is desirable that the terminals be reusable over many cycles of such use and still not only retain the ability to reliably displace insulation from the conductors, but also maintain good conductive contact with the conductor with sufficient pullout resistance. Such pullout resistance must be such as to prevent the conductor from coming out of the terminal due to vibration or pulling forces which may be exerted during other related work on adjacent conductors and/or equipment.